The subject matter of the invention described and claimed herein is related to the subject matter of U.S. patent application Ser. No. 915,669, filed June 15, 1978, now abandoned, and co-pending U.S. patent application Ser. No. 107,738 filed Dec. 27, 1979, now U.S. Pat. No. 4,307,731, issued Dec. 29, 1981 which applications are hereby incorporated by reference in their entirety.
Generally speaking, this invention relates to blood sampling devices. More particularly, this invention relates to such devices for taking multiple sample collections. Many different forms of valve assemblies have been designed in the past for controlling the direction of flow of fluids. These include, for example, ball and seat valves, duck bill valves, and cup-shaped or conical valves. It is the latter form of valve to which this invention is directed and such valves operate by compressing or folding their elastomeric skirts under sufficient pressure for permitting fluids to pass by around the skirt. Flow of fluid in the opposite direction, toward the center of the skirt has the effect of expanding the flexible skirt portion into sealing contact with the adjacent cooperating walls in the chamber where the skirt valve is fixed. U.S. Pat. No. 2,913,000, for example, discloses a cup-shaped flow control valve which operates in this manner.
While such cup valves have proved useful in multiple blood sampling assemblies, enabling the user to exchange evacuated blood collection tubes without undo leakage due to venous or tourniquet pressure, and while such assemblies have provided simple, inexpensive arrangements, they have not been entirely satisfactory in that the degree of leakage has been somewhat too high in some applications, and the support arrangement for the cup valve has not been substantial enough and configured in a manner whereby prevention of cocking of the valve is completely achieved.
With this invention, by contrast, a cup valve arrangement is provided which has the effect of reducing substantially to zero any leakage around the circumferential bottom edge of the skirt of the cup valve and, simultaneously, reducing the cocking of the valve from its normal position to acceptable limits. This is achieved by incorporating an annular spike or sealing ring adjacent the bottom edge of the skirt of the valve for enhancing the sealing effect between the valve skirt and the adjacent cooperating valve chamber walls. In addition, the internal pedestal support for the valve has been enlarged and reconfigured to provide a more substantial support for the cup valve, for reducing any cocking thereof.
It is, therefore, among the primary objects of the invention to provide a blood sampling assembly with a valve member having a resilient skirt which has both a multiple sampling feature and the capability of acting as a check valve.
It is a further object of the invention to provide a valve member with means which reduces to a minimum any cocking of the valve from its normal position. A still further object of the invention is to provide a cup-shaped check valve which operates to reduce substantially to zero any leakage around the valve in its closed position. A further object of the invention is to provide a cup-shaped check valve and a blood sampling assembly therefore which may be mass produced in economical fashion.
The valve assembly, in accordance herewith, has a resilient skirt which will collapse under sufficient pressure in one direction of flow, and which will expand against the walls of a fluid conduit or chamber in which it is positioned to prevent flow in the opposite direction. Positioned centrally of the cup valve along the axis thereof is a protrusion which serves to cooperate with the pedestal support therefore to provide the support for the cup valve, in accordance herewith, in its various positions of operation.
Before describing this invention in more detail, it may be well to note that the cup valve of the invention may be comprised of any conventional elastomer, such as natural or synthetic rubber. Satisfactory results have been achieved, in accordance herewith, with a natural rubber formulation number VL601M105 manufactured by Vernay Laboratories, Inc., Yellow Springs, Ohio.
An advantage of the invention herein, as applied to multiple sampling needles, is that the one-way cup-valve prevents chemical additives within an evacuated container attached to the assembly, in accordance herewith, from entering the bloodstream. If a tourniquet is removed or loosened before the intravenous needle is withdrawn from the vein, a reverse pressure could cause backflow. With the improved structure, in accordance herewith, such a risk is eliminated. That is, the circumferential spike together with the bottom of the skirt of the cup valve in accordance herewith, when viewed in section, is in the form of a ring under compression. Any deflection thereof inwardly, causes convolution of that ring. By incorporating the spike, in accordance herewith, the degree of convolution is reduced, thus eliminating leakage between the cooperating surfaces of the cup valve and its adjacent chamber walls in the sealing position thereof. In addition, the invention herein includes a substantially larger and differently configured pedestal centrally of the cup valve which serves as the support for the cup valve. This larger negative pressure hub pedestal has the effect of maintaining the valve "squared". That is, the axis of the cup-shaped valve is maintained adjacent the axis of the pedestal support which supports it.
Other objects and advantages of this invention will be apparent from the following description, the accompanying drawings and the appended claims.